Demolition shear and demolition shear piercing tip insert and nose configuration

ABSTRACT

A demolition shear and a piercing tip insert and nose configuration for a demolition shear which resists nose wear and resists retract forces exerted on the piercing tip insert in jamming situations and in the event of snagging of the piercing tip insert. The piercing tip insert includes first and second piercing tip halves, each half having an outer planar sidewall, a curved front wall extending laterally inward, and a bottom leg extending laterally inward defining a shearing edge and a piercing edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/783,547 filed Oct. 9, 2015 which is a national stage entry ofInternational Application No. PCT/US2013/035816 filed Apr. 9, 2013, eachof which is incorporated herein in its entirety.

BACKGROUND

There is a need for a demolition shear having a piercing tip insert andnose configuration to reduce nose wear and to resist retract forcesexerted on the piercing tip insert in jamming situations and in theevent of snagging of the piercing tip insert.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a right side perspective view (from the position of theoperator) of one embodiment of a demolition shear attachment.

FIG. 2 is a left side perspective view of the demolition shearattachment of FIG. 1.

FIG. 3 illustrates the shear attachment of FIG. 1 in a typical operatingposition showing the movement of the upper jaw with respect to the lowerjaw during a shearing operation.

FIG. 4 is an exploded perspective view of the jaw pivot shaft of theshear attachment of FIG. 1

FIG. 5 is an enlarged view of FIG. 1 showing the jaws of the shearattachment.

FIG. 6 is the same view as FIG. 5 but with the blade inserts andpiercing tip inserts removed.

FIG. 7 is an enlarged view of FIG. 2 showing the jaws of the shearattachment.

FIG. 8 is a perspective view of the lower jaw of FIG. 1 with the upperjaw removed to better show the blade-side shear blade inserts and guideblade insert.

FIG. 9 is another perspective view of the lower jaw of FIG. 1 with theupper jaw removed to show guide-side guide blade insert and cross-bladeinsert.

FIG. 10 is the same view as FIG. 7 with the blade inserts and piercingtip insert removed.

FIG. 11 is the same view of the lower jaw as FIG. 9 with the bladeinserts removed.

FIG. 12 shows different views of an embodiment of a shear blade insert,wherein 12A is a front perspective view, 12B is a front elevation view,12C is an end elevation view and 12D is rear elevation view.

FIG. 13 shows different views of an embodiment of a guide blade insert,wherein 13A is a front perspective view, 13B is a front elevation view,13C is an end elevation view and 13D is rear elevation view.

FIG. 14 shows different views of an embodiment of a cross-blade insert,wherein 14A is a front perspective view, 14B is a rear perspective view,14C is an end elevation view, 14D is a front elevation view and 14E isrear elevation view.

FIG. 15 shows different views of an embodiment of a blade-side piercingtip half, wherein 15A is a front perspective view, 15B is a rearperspective view, 15C is a front end elevation view, 15D is an outerside elevation view and 15E is an inner side elevation view.

FIG. 16 shows different views of an embodiment of a guide-side piercingtip half, wherein 16A is a front perspective view, 16B is a rearperspective view, 16C is a front end elevation view, 16D is a inner sideelevation view and 16E is outer side elevation view.

FIG. 17 is a perspective view of the upper jaw of the shear attachmentof FIG. 1 in isolation with the piercing tip inserts shown exploded withrespect to the nose seat.

FIG. 18 is an enlarged side elevation view of the upper and lower jawsof the shear attachment of FIG. 1 with the upper jaw in the fully openposition.

FIG. 19 is an enlarged side elevation view of the upper and lower jawsof the shear attachment of FIG. 1 with the upper jaw in a partiallyclosed position.

FIG. 20 is an enlarged side elevation view of the upper and lower jawsof the shear attachment of FIG. 1 with the upper jaw about to enter theslot in the lower jaw.

FIG. 21 is an enlarged side elevation view of the upper and lower jawsof the shear attachment of FIG. 1 with the upper jaw fully closed andextending into the slot of the lower jaw.

FIG. 22 is an enlarged side elevation view of the upper and lower jawillustrating forces acting on the piercing tip in a jamming situation.

FIG. 23 is an enlarged side elevation view of the upper and lower jawillustrating forces acting on the piercing tip in another type ofjamming situation.

FIG. 24 is an enlarged side elevation view of the upper and lower jawillustrating forces acting on the piercing tip in the event of snaggingof the upper end of the piercing tip due to wear of the parent materialfrom the nose of the upper jaw.

DESCRIPTION

Referring to the drawings wherein like reference numerals designate thesame or corresponding parts throughout the several views, FIGS. 1 and 2are perspective views from right and left sides, respectively (from theposition of the operator), of one embodiment of a demolition shearattachment 10. The shear attachment 10 has a main body 12 with a forwardend 14 and a rearward end 16. The rearward end 16 is adapted to beoperably mounted to the boom or stick 18 (FIG. 3A) of an excavator suchas by a swivel attachment 19 or other suitable mounting attachment asrecocognized and understood by those of skill in the art. At the forwardend 14 of the main body 12 is a movable upper jaw 40 and a fixed lower42 (discussed in detail later).

FIGS. 3A-3C show the shear attachment 10 mounted to the boom or stick ofan excavator 18 of an excavator, and positioned in a typical operatingposition, and illustrating the movement of the upper jaw 40 closing withrespect to the lower jaw 42 over an object 11 to be sheared. The object11 to be sheared may be any structural member, such as a steel I-beam orchannel, steel plate, pipe or some other material, such as scrap metal,sheet metal or any other object or material for which a demolition shearis suited for handling or processing.

Referring to FIGS. 1-4, the main body 12 is typically constructed ofsteel side plates 20, 22, a top plate 24 and a bottom plate 26 whichtogether define a substantially enclosed area within which a hydraulicactuator 30 (FIGS. 3A-3C) and other hydraulic components of the shearattachment 10 are substantially enclosed and protected. The hydraulicactuator 30 is pivotally secured at a rearward end within the main body12 by an actuator pivot pin 32 extending through the side plates 20, 22,internal gussets (not shown) and the cylinder rod clevis 34. The forwardend of the hydraulic actuator 30 is pivotally attached to the movableupper jaw 40 by a cylinder pin 36 extending through the cylinder bodyclevis 38 and cylinder pin bore 39 (see also FIG. 17) in a rearward lobeof the upper jaw 40. Thus, it should also be appreciated, that as thehydraulic actuator 30 extends and retracts as illustrated in FIGS.3A-3C, the upper jaw 40 rotates about the longitudinal axis of the jawpivot shaft assembly 60 (discussed below) to open and close the upperjaw 40 with respect to the lower jaw 42. An access opening with anaccess cover 25 (FIG. 2) may be provided in the top plate to gain accessto the interior of the body 12 for installation, maintenance, servicingand repair of the hydraulic actuator and other components of thehydraulic system.

As best illustrated in FIGS. 4, 8 and 9, jaw bosses 44, 46 on each sideof the forward end 14 of the main body 12 include hub bores 48, 50. Ajaw pivot shaft assembly 60 received within the hub bores 48, 50 andthrough a pivot shaft bore 54 (see FIG. 17) pivotally supports the upperjaw 40.

The jaw pivot shaft assembly 60 comprises flanged bushings 56, 58 fittedwithin the hub bores 48, 50. A main shaft 62 is press-fit into the pivotshaft bore 54 for rotation with the upper jaw 40. The main shaft 62includes a central bore 64 which receives a tie rod 66 having threadedends 68. End caps 70, 72 are secured to the flanged bushings 56, 58 bythreaded connectors extending through aligned holes in the flangebushings 56, 58 and are threadably received by aligned internallythreaded holes in the hubs 44, 46. Tie rod nuts 74 threadably receivethe threaded ends 68 of the tie rods 66. The tie rod nuts 74 are securedto the end caps 70, 72 by threaded connectors threadably received intointernally threaded aligned holes in the flange bushings 56, 58. Itshould be appreciated that the tie rod 66 and tie rod nuts 74 laterallyrestrain the hubs 48, 50 against lateral forces exerted on the jawsduring the shearing operation.

As best viewed in FIGS. 4 and 8, lateral jaw stabilizing puck assemblies80, such as disclosed in U.S. Pat. No. 7,216,575, may be provided alongwith corresponding wear plates or wear surfaces 82 (FIG. 17) on theadjacent side or sides of the upper jaw 40 to resist lateral movement ofthe upper jaw 40 during the shearing operation until the upper jawenters the slot 96 of the lower jaw 42 (discussed below).

Referring to FIGS. 5-11, the lower jaw 42 includes forwardly extending,laterally spaced and substantially parallel jaw beams 90, 92 and across-beam 94 extending transversely between the forward ends of thelaterally spaced jaw beams 90, 92. The laterally spaced jaw beams 90, 92and the cross beam 94 together define a slot 96 into which the upper jaw40 is received during the shearing process (see FIG. 3C and FIG. 4). Asdiscussed in more detail below, the forwardly extending jaw beam 90 isadapted to receive shear blade inserts and guide blade inserts and ishereinafter referred to as the blade-side jaw beam 90. The otherforwardly extending jaw beam 92 serves to provide structural rigidity tothe lower jaw and also serves to laterally restrain and guide the upperjaw into the slot 96 during the shearing process and is hereinafterreferred to as the guide-side jaw beam 92.

As best viewed in FIG. 10, the inner side of the blade-side jaw beam 90includes a shear blade seat 100 which is adapted to receive a set ofhardened steel shear blade inserts 110 (FIGS. 7 and 8). An embodiment ofthe shear blade inserts 110 is illustrated in FIG. 12. The shear bladeinserts 110 each have generally planar vertical wear surfaces 114, 116and generally planar horizontal wear surfaces 118, 120. The intersectionof the vertical and horizontal wear surfaces define four shearing edges122. The shear blade inserts 110 have parallel sloping end surfaces 124,126 creating a parallelogram configuration so that when the shear bladeinserts 110 are positioned and oriented in the shear blade seat 100 theadjacent end surfaces bear against each another in a downward apex (seeFIGS. 7 and 8). It should be appreciated, that because the shear bladeinserts 110 are in the shape of identical parallelepiped, they may berotated and oriented with respect to one another within the shear bladeseat 100 so that all four shearing edges 122 may be used as the shearingedges wear during use. The planar vertical wear surfaces 114, 116include counterbore holes 130 for receiving threaded connectors 132(preferably socket headed cap screws) to removably attach the shearblade inserts 110 within the shear blade seat 100. The counterbore holes130 permit the heads of the threaded connectors 132 to be seated withinthe counterbore. The threaded ends of the threaded connectors 132 extendthrough the counterbore holes 130 and through aligned holes 134 (FIG.10) in the shear blade seat 100 and are secured by nuts 136 (FIGS. 5 and9), received within counterbore holes 138 on the outer side of theblade-side jaw beam 90.

As best viewed in FIG. 10, the inner side of the blade-side jaw beam 90also includes a guide blade seat 200 which is adapted to receive ahardened steel guide blade insert 210 (best viewed in FIG. 8). Anembodiment of the guide blade insert 210 is illustrated in FIG. 13. Theguide blade insert 210 has generally planar vertical wear surfaces 214,216 and generally planar horizontal wear surfaces 218, 220. Theintersections of the vertical and horizontal wear surfaces define fourshearing edges 222. The guide blade insert 210 has parallel sloping endsurfaces 224, 226 creating a parallelogram configurations. The slopingend surfaces 224, 226 of the guide blade insert 210 are complimentary tothe sloping end surfaces 124, 126 of the shear blade inserts 110 so thatwhen the guide blade insert 210 is positioned and oriented in the guideblade seat 200 one of its end surfaces 224, 226 will bear against one ofthe end surfaces 124, 126 of the adjacently positioned shear bladeinsert 110 (as best illustrated in FIG. 8). It should be appreciated,that because the guide blade insert 210 is in the shape of aparallelepiped, it may be rotated and oriented within the guide bladeseat 200 (and switched with the guide-side guide blade seat 300discussed below) so that all four shearing edges 222 may be used as theshearing edges wear during use. The vertical wear surfaces 214, 216include tapped internally threaded holes 230 for receiving threadedconnectors 232 (e.g., bolts) to removably attach the guide blade insert210 within the guide blade seat 200. The threaded ends of the threadedconnectors 232 extend through aligned counterbore holes 234 (FIGS. 5 and9) on the outer side of the blade-side beam 90 and are threadablyreceived by the tapped internally threaded holes 230 in the guide bladeinsert 210.

As best viewed in FIGS. 9 and 11, the guide-side beam 92 also includes aguide-blade seat 300 (FIG. 11) which is adapted to receive the sameguide blade insert 210 as received in the blade-side guide blade seat200 so that the guide blade inserts 210 are interchangeable between theguide-side guide blade seat 300 and the blade-side guide blade seat 200.Accordingly, the guide blade insert 210 is retained and secured in theguide-side guide blade seat 300 in substantially the same manner as theblade-side guide blade seat 200 in that the same threaded connectors 232(e.g., bolts) extend through aligned counterbore holes 334 (FIGS. 7, 8,10) on the outer side of the guide-side jaw beam 92 and are threadablyreceived by the tapped holes 230 in the guide blade insert 210.

As best viewed in FIGS. 9 and 11, the cross-beam 94 includes across-blade seat 400 (FIG. 11) which is adapted to receive a hardenedsteel cross-blade insert 410 (FIG. 9). An embodiment of the cross-bladeinsert 410 is illustrated in FIG. 14. The cross-blade insert 410 has agenerally planar front wear surface 414, generally planar top and bottomwear surfaces 418, 420, generally planar end surfaces 424, 426 and aback side 428. The back side 428 includes four equally radially spacedinternally threaded holes 430. The back side 428 is also keyed with aprojection 432 which seats within a recess 434 (FIG. 11) in thecross-blade seat 400. The intersection of the front vertical wearsurface 414 with the top and bottom wear surfaces 418, 420 and endsurfaces define four cutting edges 422. The cross-blade insert 410 ispreferably square with four radially spaced holes 430 so that it may berotated 90 degrees four times within the cross-blade seat 400 so thatall four cutting edges 422 may be used as the shearing edges wear duringuse. The cross-blade insert 410 is secured within the cross-blade seat400 by threaded connectors 434 (such as bolts) extending throughcounterbore holes 436 (FIGS. 5 and 7) in the cross-beam 94. The ends ofthe threaded connectors 434 are received within the aligned internallythreaded holes 430 in the back side surface 428 of cross-blade insert410.

The upper jaw 40 has a blade-side and a guide-side which correspond tothe adjacent blade-side jaw beam 90 and guide-side beam 92 of the lowerjaw 42. The blade-side of the upper jaw 40 includes a shear blade seat500 (FIG. 6) which is adapted to receive the same shear blade inserts110 (FIG. 5) as used in the shear blade seat 100 of the lower jaw 42 sothat the shear blade inserts 110 are interchangeable between the upperand lower jaws, thereby reducing the number of different bladeconfigurations needed for the shear attachment 10. However, in the upperjaw, the shear blade inserts 110 are oriented in an upward apex asopposed to the downward apex in the lower jaw (compare FIGS. 5 and 7).The shear blade inserts 110 are secured in the upper jaw insubstantially the same manner as the lower jaw. The threaded ends of thethreaded connectors 132 extend through the counterbore holes 130 andthrough aligned holes 534 in the upper shear blade seat 500 and aresecured by nuts 136 received within counterbores 538 (FIG. 7) on theguide-side of the upper jaw 40.

Referring to FIGS. 6, 10 and 17, the forward most end of the upper jaw40 or nose 601 includes a nose seat 600 adapted to receive a hardenedsteel piercing tip insert 610 (FIGS. 5, 7, 17) to protect the parentmaterial of the upper jaw nose from wear during use. The nose seat 600includes a blade-side nose seat 602 (FIGS. 6 and 17), a guide-side noseseat 604 (FIG. 10), and a front nose seat 606 (FIGS. 6, 10, 17) whichresults in a narrowed nose portion 608. The forward most nose tip 609 ofthe nose seat 600 is preferably radiused to minimize stressconcentrations on the nose portion 608, both during the manufacturingprocess and during use. The piercing tip insert 610 is comprised of twohalves 620, 622 which are substantially mirror images of each otherexcept for the connector holes in each half (discussed later). The halfwhich extends over the blade-side of the nose is hereinafter referred toas the blade-side half 620, and the half which extends over theguide-side of the nose is hereinafter referred to as the guide-side half622.

FIG. 15 shows various views of an embodiment of the blade-side half 620.FIG. 16 shows similar views of an embodiment of the guide-side half 622.Each of the piercing tip halves 620, 622 includes an outer sidewall 630having a substantially planar vertical wear surface 632 and asubstantially planar vertical inner bearing surface 634. Each half 620,622 also includes a laterally inward projecting front wall 636 having anouter curved wear surface 638 and an inner bearing surface 640. Eachpiercing tip half 620, 622 also includes a laterally inward projectingbottom leg 642 having a bottom planar wear surface 644 and an upper legbearing surface 646. Each of the piercing tip halves 620, 622 furtherincludes an end bearing surface 648 and an ear 650 having upper earbearing surface 651 and a lower ear bearing surface 653. The ear 650 mayhave a radiused periphery to reduce stress concentrations. The lower earbearing surface 653 extends rearwardly of the end bearing surface 648,the purpose of which is discussed later in connection with FIGS. 22 and23. The intersection of the planar vertical wear surface 632 and thebottom planar wear surface 644 defines a shearing edge 652. Theintersection of the curved wear surface 638 of the front wall 636 andthe bottom planar wear surface 644 defines a front piercing edge 654(the front piercing edge may be chamfered).

As best viewed in FIGS. 6, 10 and 17, the nose seats 602, 604, 606define peripheral bearing edge surfaces 656 which complimentarilyreceive the outer peripheries of the piercing tip halves 620, 622. Itshould be appreciated that the inner surface 640 of the laterally inwardprojecting front wall 636 and the upper surface 646 of the laterallyinward projecting bottom leg 642 of each piercing tip half 620, 622 isapproximately half the width of the narrowed nose portion 608 so thatwhen the piercing tip halves 620, 622 are mounted in the nose seat 600,the inner bearing surfaces 640 of the sidewalls 630 and the upper legbearing surfaces 646 of the bottom legs 642 of the piercing tip halves620, 622 bear against the respective bearing surfaces of the blade-sidenose seat 602, the guide-side nose seat 604 and the front nose seat 606.Additionally, the upper ear bearing surface 651 and the lower earbearing surface 653 of the tip halves 620, 622 bear against peripheralbearing edge surfaces 656 of the nose seat 600. On the blade-side of thenose 601, one of the sloping ends 124, 126 (depending on orientation) ofthe upper shear blade insert 110 abuts and bears against the back endbearing surface 648 of the blade-side half 620. As such, the blade-sidepiercing tip half 620 is rotationally restrained from outward rotation(as discussed later) by both the blade insert 110 and the peripheralbearing edge surfaces 656 which mateably receive of the upper earbearing surface 651 and the lower ear bearing surface 653 of theblade-side nose seat. The guide-side piercing tip half 622 isrotationally restrained from movement by the peripheral bearing edgesurfaces 656 which mateably receive of the upper ear bearing surface 651and the lower ear bearing surface 653 of the guide-side nose seat 604.

It should be appreciated that when the two piercing tip halves 620, 622are mounted in the nose seat 600, the narrowed nose portion 608 iscompletely surrounded by the hardened steel piercing tip insert 610thereby protecting the parent material of the nose 601 from wear duringuse.

In addition to being rotationally restrained by the peripheral bearingedge surfaces 656, the two piercing tip halves 620, 622 are secured tothe narrowed nose tip 608 with threaded connectors 670. In a preferredembodiment, the threaded connectors are socket headed cap screws. Thetwo halves 620, 622 include aligned holes 660 through their respectiveouter sidewalls 632. Corresponding aligned holes 664 are providedthrough the narrowed nose tip 608. Concentric counterbores 668 areprovided over the holes 660 in the outer wall 632 of the blade-side half620. The aligned holes 660 in the outer wall 632 of the guide-side half622 are tapped with internal threads. The counterbores 668 permit theheads of the threaded connectors 670 to be seated within thecounterbores 668. The threaded ends of the threaded connectors 670extend through the holes 660 in blade-side half 620 and through thealigned holes 664 in the narrow nose tip 608 and are threadably receivedby the internally threaded aligned holes 660 of the guide-side tip half622. Obviously, the counterbores 668 and the internal threaded holes 660in the two tip halves 620, 622 could be reversed if desired.Alternatively, counterbores 668 could be provided in outer walls 632 ofboth tip halves 620, 622 for receiving the heads of the threadedconnectors 670 and to receive a nut (not shown) on the opposing tip halfrather than tapping the holes 660 of one of the halves. As discussed inmore detail later in connection with FIGS. 18 and 22, the holes 660, 664are aligned along an arc concentric with the front edge of the piercingtip 610 (i.e., the outer curved wear surface 638) to ensure a moreuniform loading across the threaded connectors 670.

It should be appreciated that when mounted to the upper jaw 40, theplanar vertical wear surfaces 114, 116 (depending on orientation) of theshear blade inserts 110 are substantially coplanar with the verticalwear surface 632 of the blade-side tip half 620 and the shearing edges122, 652 of the shear blade inserts 110 and piercing tip insert 610 aresubstantially aligned. Similarly, on the lower jaw 42, the planarvertical wear surfaces 114, 116 (depending on orientation) of the shearblade inserts 110 are substantially coplanar with the vertical wearsurface 214 of the blade-side guide blade insert 210 and theirrespective shearing edges 122, 222 are substantially aligned. It shouldalso be appreciated that the substantially coplanar vertical wearsurfaces 114, 116, 632 and shearing edges 122, 652 of the upper shearblade inserts and piercing tip insert 610 are slightly laterally,inwardly offset from the shearing edges 122, 232 of the shear bladeinserts 110 and blade-side guide blade insert 210 of the lower jaw(preferably between a range of about 0.01 inches and 0.05 inches), topermit the upper shearing edges to pass by the shearing edges of thelower jaw as the upper jaw moves through its range of motion and intothe slot 96 of the lower jaw 42. Likewise, the shearing edge 652 of theguide-side piercing tip half 622 is laterally inwardly offset from theshearing edge 222 of the guide-side guide blade insert 210 preferablybetween a range of about 0.01 inches and 0.05 inches. Accordingly, thewidth of the piercing tip insert 610 is less than the width between theopposing shearing edges 222 of the blade-side and guide-side guideblades 210 (preferably between a range of about 0.02 and 0.1 inches),such that the piercing tip insert 610 can pass between the lower dualguide blades 210 as the upper jaw closes into the slot 96 of the lowerjaw 42. Shims may be inserted between the various inserts 110, 210, 610and their respective seats 100, 200, 300, 500, 600 to maintain the closetolerances between the respective shearing edges.

FIGS. 18-22 are enlarged side elevation views of the jaws 40, 42 tobetter illustrate the relationship of the blade inserts 110, 210 andpiercing tip insert 610 cross-blade insert 410 during movement of theupper jaw—i.e., from the fully open position (FIG. 18), to the fullyclosed position (FIG. 21) in which the upper jaw reaches full depth intothe slot 96 of the lower jaw 42. FIG. 19, shows the upper jaw partiallyclosed wherein the front piercing edge 654 of the piercing tip insert610 is perpendicular or normal to the ground surface. FIG. 20, shows theupper jaw in a position where the front piercing edge 654 intersects thelower jaw 42.

A nose wear shoe 700 is secured (such as by welding) to the nose 601 ofthe upper jaw 40 above the piercing tip insert 610 to protect the parentmaterial of the upper jaw from wear during use. As the nose wear shoe700 wears down, it may be removed and replaced with another wear shoe700. The wear shoe 700 may be fabricated from the same material as theparent material or it may be fabricated from hardened steel. Referringto FIG. 20, the nose wear shoe preferably extends along the nose asufficient distance to ensure that the parent material of the nose isprotected to at least the full depth of entry of the upper jaw 40 intothe lower jaw 42. In an alternative embodiment, the piercing tip insert610 may be extended along the nose 601 to the full dept of entry of theupper jaw into the lower jaw. In such an embodiment, the nose seat 600would likewise be extended and additional holes 660 may be necessary toadequately restrain the longer piercing tip insert 610 to the narrowednose 608.

It should be appreciated that the parent material of the nose 601 abovethe piercing tip insert 610 is more susceptible to wear than thehardened steel piercing tip insert 610. Accordingly, without a wear shoe700, the nose 601 could wear down to the point that the upper edge ofthe piercing tip insert 610 projects above the nose. If the upper edgeof the piercing tip insert 610 projects outwardly from the nose 601, theprojection could potentially snag on material caught in the jaws as theupper jaw re-opens or is retracted from the lower jaw. If sufficientretract force is exerted on the upper jaw, the piercing tip insert couldbe pulled away from the nose by the snagged material, shearing thethreaded connectors in the process or breaking the piercing tip insert.Accordingly, as hereinafter described, the nose 601 of the upper jaw isconfigured to minimize the risk of snagging, even when a wear shoe 700is not mounted to the nose 601 or where the wear shoe itself is worndown such that the parent material of the nose is no longer protected bythe wear shoe.

FIGS. 18 and 21 illustrate a preferred configuration of the nose 601 toavoid or minimize occurrences of snagging. The phantom line designatedby reference numeral 800 identifies the arc created by the forward mostfront piercing tip edge 654 of the piercing tip insert 610 as the upperjaw moves through its range of motion. The arc 800 has a radius R1 tothe center axis of the jaw pivot shaft 60. The outermost periphery ofthe nose 601 from the forward piercing edge 654 of the piercing tip 610to the end of the nose wear shoe 700 or to the point on the nose whichcorresponds to the maximum depth that the nose 601 penetrates the lowerjaw is configured to transitions away from the front piercing tip edgearc 800 in a substantially smooth nose arc 802. The nose arc 802 has aradius R2 which is less than the radius R1, such that radial distancesfrom the central axis of the jaw pivot shaft 60 to points along the nose601 or nose arc 802 continually decrease relative to the front piercingtip edge arc 800. Stated another way, the distance between the piercingtip front edge arc 800 and the nose arc 802 continually increases alongthe nose 601 or nose arc 802 from the piercing tip front edge 654. Thisconfiguration allows the nose 601 to only make contact at the piercingtip front edge 654, thereby avoiding or reducing the likelihood of thenose 601 scraping along objects being pierced by the piercing tip 610,thereby minimizing wear along the nose. Additionally, because the noseincreasingly transitions away from the piercing tip edge arc 800, itreduces the likelihood of snagging of material caught in the jaws evenif the parent material of the nose becomes worn down to where the upperedge of the piercing tip insert 610 projects outwardly from the wornparent material of the nose.

Furthermore, the piercing tip seat 600 and piercing tip insert 610 areconfigured to ensure retention of the piercing tip if a projecting edgeof the piercing tip becomes snagged or if the upper jaw becomes jammedby material trapped in the jaws. For example, in FIG. 22 the hatchedarea 900 is intended to represent trapped or lodged material caughtbetween the wear surfaces of the piercing tip insert 610 and the guideshear blade inserts 210 causing the upper jaw to become jammed withinthe slot 96 of the lower jaw 42 such that the upper jaw 40 cannotretract or re-open. The retract force F of the upper jaw 40 (exerted bythe hydraulic actuator 30 pulling on the upper jaw) attempts to pull thepiercing tip insert 610 in the direction perpendicular to the radialline 806 extending from the center axis of the jaw pivot shaft 60 to themidpoint of the trapped material 900. It should therefore be appreciatedthat any bearing surface which is less than 90 degrees to the radialline 806, will resist the retract force F. Accordingly, the rearwardlyprojecting ears 650 of the piercing tip insert 610 ensure that a bearingsurface is provided to resist the retract force F.

Referring to FIG. 22, the lower ear bearing surface 653 is at an angleless than 90 degrees to the radial line 806 and therefore provides abearing surface designated by arrows R against which the peripheralbearing edge surfaces 656 of the nose seat 600 engage to resist theretract force F. Similarly, the inner bearing surface 640 of the frontwall 636 bears against the nose seat 606 as designated by arrows R toresist the retract force F. Thus, the resistance or reactionary forces Rwill reduce the shearing forces being exerted on the connectors 670 bythe retract force F, thereby preventing or minimizing the piercing tipinsert 610 from being pulled off the nose or otherwise fracturing.

Furthermore, because the holes 660 in the piercing tip insert 610 arealigned along an arc 804 having a radius R3 which is less than theradius R2 but which is concentric with the nose arc 802, a more uniformload is applied across all of the connectors 670 thereby furtherreducing the shearing stresses exerted on any one connector or causingstress concentrations which could shear the connectors or cause thepiercing tip insert to fracture.

FIG. 23 illustrates another example wherein the hatched area 902 isintended to represent material trapped between the piercing tip insert610 and the cross-blade insert 410. In this example, the retract force Fagain pulls the piercing tip in the direction perpendicular to theradial line from 806 extending from the center axis of the jaw pivotshaft 60 to the center point the trapped material, which, in thisexample, is assumed to be at the piercing tip front edge 654. Theretract force F will cause the piercing tip insert 610 to attempt toroll outwardly or away from the nose 601 as indicated by arrow 810.However, the upper ear bearing surface 651 engages with the peripheralbearing edge surfaces 656 of the nose seat 600 as designated byreactionary forces R to resist the outward rotation of the piercing tipinsert 610 thereby reducing shearing forces on the connectors 670 andpreventing or reducing stress fracturing of the piercing tip insert 610.

FIG. 24 illustrates an example of the retract force F acting on theupper edge of the piercing tip insert 610 in the unlikely event that thenose 601 is worn down to create a ridge upon which material could snagas described above. Such an occurrence is unlikely in view of theconfiguration of the nose 601 having a continually increasing distancebetween the nose arc 802 and the piercing tip front edge arc 800 for thereasons explained above, but nevertheless, if the nose is worn down tocreate a ridge on which material could snag, the upper ear bearingsurface 651 would engage against the peripheral bearing edge surfaces656 of the nose seat 600 as indicated by reaction forces R to resist theretract force F attempting to roll the piercing tip edge outwardly asindicated by arrow 810 thereby reducing shearing forces on theconnectors 670 and preventing or reducing stress fracturing of thepiercing tip insert 610.

The foregoing description is presented to enable one of ordinary skillin the art to make and use the invention and is provided in the contextof a patent application and its requirements. Various modifications tothe embodiments described herein, and the general principles andfeatures of the embodiments described herein will be readily apparent tothose of skill in the art. Thus, the present invention is not to belimited to the embodiments described herein and illustrated in thedrawing figures, but is to be accorded the widest scope consistent withthe spirit and scope of the appended claims.

1. A piercing tip insert for a demolition shear having an upper jawpivotable over a range of motion between an open position and a closedposition with respect to a lower jaw, the upper jaw having a forwardmost tip portion defining a nose, the nose having a blade-side, aguide-side, a bottom side and a front side, the piercing tip insertcomprising: a blade-side outer planar sidewall surface; a guide-sideouter planar sidewall surface; a bottom surface extending laterallybetween a bottom side of said blade-side outer planar sidewall surfaceand a bottom side of said guide-side outer planar sidewall surface; acurved outer front wall surface extending laterally between a front sideof said blade-side outer planar sidewall surface and a front side ofsaid guide-side outer planar sidewall surface, said curved outer frontwall surface having a front wall arc radius; whereby when mounted ontothe nose of the upper jaw, the nose is completely surrounded andprotected along the blade-side of the nose by said blade-side outerplanar sidewall surface, along the guide-side of the nose by saidguide-side outer planar sidewall surface, along the bottom side of thenose by said bottom surface, and along the front side of the nose bysaid curved outer front wall surface.
 2. The piercing tip insert ofclaim 1, wherein an intersection of said blade-side outer planarsidewall surface and said bottom surface defines a shearing edge andwherein an intersection of said curved outer front wall surface and saidbottom surface defines a front piercing edge.
 3. The piercing tip insertof claim 1, wherein each of said blade-side and said guide side outerplanar sidewall surfaces includes a plurality of connector holes eachadapted to receive a threaded connector for securing said piercing tipinsert onto said nose, said connector holes disposed along a connectorhole arc concentric with said front wall arc, said connector hole archaving a connector hole arc radius which is less than said front wallarc radius.
 4. The piercing tip insert of claim 1, wherein said piercingtip insert includes a first piercing tip portion and a second piercingtip portion.
 5. The piercing tip insert of claim 4, wherein said firstpiercing tip portion and said second piercing tip portion comprisemating halves of said piercing tip insert.
 6. A demolition shear,comprising: an upper jaw pivotable over a range of motion between anopen position and a closed position with respect to a lower jaw, saidupper jaw having a forward most tip portion defining a nose, the nosehaving a blade-side, a guide-side, a bottom side and a front side; apiercing tip insert including: a blade-side outer planar sidewallsurface; a guide-side outer planar sidewall surface; a bottom surfaceextending laterally between a bottom side of said blade-side outerplanar sidewall surface and a bottom side of said guide-side outerplanar sidewall surface; a curved outer front wall surface extendinglaterally between a front side of said blade-side outer planar sidewallsurface and a front side of said guide-side outer planar sidewallsurface, said curved outer front wall surface having a front wall arcradius; whereby said nose is completely surrounded and protected by saidpiercing tip insert along the blade-side of said nose by said blade-sideouter planar sidewall surface, along said guide-side of said nose bysaid guide-side outer planar sidewall surface, along said bottom side ofsaid nose by said bottom surface, and along said front side of said noseby said curved outer front wall surface.
 7. The demolition shear ofclaim 6, wherein an intersection of said blade-side outer planarsidewall surface and said bottom surface defines a shearing edge andwherein an intersection of said curved outer front wall surface and saidbottom surface defines a front piercing edge.
 8. The demolition shear ofclaim 6, wherein each of said blade-side and said guide side outerplanar sidewall surfaces includes a plurality of connector holes eachadapted to receive a threaded connector for securing said piercing tipinsert onto said nose, said connector holes disposed along a connectorhole arc concentric with said front wall arc, said connector hole archaving a connector hole arc radius which is less than said front wallarc radius.
 9. The demolition shear of claim 6, wherein said piercingtip insert includes a first piercing tip portion and a second piercingtip portion.
 10. The demolition shear of claim 9, wherein said firstpiercing tip portion and said second piercing tip portion comprisemating halves of said piercing tip insert.
 11. The demolition shear ofclaim 6, wherein as said upper jaw pivots through said range of motion,said front piercing edge defines a piercing edge arc having a radiuswhich is greater than said front wall arc radius such that said curvedouter front wall surface increasingly transitions away from saidpiercing edge arc.
 12. The demolition shear of claim 6, furthercomprising: a nose wear shoe having a nose wear shoe arc having a nosewear shoe radius substantially the same as said front wall arc radiussuch that said nose wear shoe arc increasingly transitions away fromsaid piercing edge arc.
 13. The demolition shear of claim 6, furthercomprising at least one shear blade mounted to said upper jaw.
 14. Thedemolition shear of claim 13, wherein said lower jaw includes at leastone shear blade.
 15. The demolition shear of claim 14, wherein saidlower jaw further includes at least one guide-blade.
 16. The demolitionshear of claim 15, wherein said lower jaw further includes at least onecross-blade.